For some wasm functions, name information is not available, resulting
in a nullptr being passed to the profiling event listener. While we
probably should have better names, this at least prevents a crash.

Change-Id: I41bd7827124e9c193a076a57d3a134f5df1d6a15
Reviewed-on: https://chromium-review.googlesource.com/926367
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51396}